Rheostat



115295213 May 24, 1927,, J A. NUGENT RHEOS TAT Filed Aug. 14 1925 I IN V EN TOR.

ATTOR Y.

'zio

Patented May 24, 1927.

UNITED STATES JOHN A. NUGENT, OF IRVINGTON, NEW JERSEY.

RH'EOSTAT.

Application filed August 14, 1925. Serial No. 50,188.

This invention relates to an improved rheostat which is designed to provide a resistance element disposed so that the contact that passes along the wire engages every part of it without any appreciable gaps, this making possible/a fine and accurate adjustment of the amount of current. fixed by the rheostat.

The invention is illustrated in (he accompanying drawing in which l igure l is a side view of a rheostat embodying my in vention. Figure 2 is a section on line 3--2 in Figure 1. Figure 3 1s a back view of the rheostat shown in Figure 1. F igure 4 5 is a perspective view of the contact and'part of the wire and Figure 5 is a top view of the wire coil shown flattened and illustrating how the contact passes along the same. The rheostat is provided with a wire of any of the usual resistance materials, the wire being disposed so that the movable contact traverses the whole length of the part of the wire that is energized. This is in direct contrast to those rheostats formed by .a coil of wire which is engaged by an arm that strikes each convolution in turn so that from one adjustment step to the other means a. clearance of a complete turn or coil of wire.

In the drawing I show the wire mounted on a suitable support which, as illustrated, is formed of a cylindrical piece of insulation on the periphery of which is arranged'the wire, which wire is formed in zig-zag shape with'the strands 11 extending first to one side and then to the other side of the support.

The wire can be fastened in any usual way but I prefer passing it on each side of a stud 12, the wire being passed over the stud and then crossed and then extending across the support to the other side to the next stud 12, the studs on one side thus being staggered relative to those on the other side. This preferred arrangement of the wire will be evident from an inspection of Figures 4 and 5. lVhere the wire crosses itself. as at 13, is where the electrical contact takes place and the small loop 14 beyond it which passes around the stud 12 is not energized.

, A contact 15 is disposed so that it moves along the wire from one end to the other and in the form shown it is a V-shaped plate with a spring pressure and is as long as the active part of the wire in its staggered or zig-zag shape and the central depressed part 16 therefor passes along the wire as shown in the drawing.

It will be evident from Figures-.4 and 5 in particular, that as the contact 15 is moved into engagement every part of the wire that is exposed to it and as the wire is drawn very tight, it forms even where it crosses, a comparatively smooth surface over which the contact can slide. It will be noted that this also permits an economy of wire as the amount looped around in the rear of the contact face in the usual commercial rheostat is saved.

The form illustrated shows the contact 15 as part of an arm 17 being preferably extended or partly looped as at 18 to give it the necessary spring action. the arm 17 being fastened to the shaft 19 which extends through the support being provided with means such as the nuts 20 for fastening it to a panel of a radio set and having the usual handle 21 and pointer 22 for operating it.

The support has the stop 23 for limiting the contact 15 so that it cannot make a complete revolution. The ends of the wire. are connected to two strips 24 to which wires can be soldered. these strips being separated by a strip of insulation 25. One of the strips 24 extends as at 26 and is in engagement with the shaft and therefor the contact arm 17.

WVhile I have shown the device as applied to a cylindrical rheostat, it will be evident that it can be. formed in other ways without departing from the scope of the invention which is fundamentally the arrangement of wire in a rheostat so that all of its energized surface can be utilized in the passage of the contact arm over it.

I claim:

A rheostat comprising a cylindrical support, a wire secured on the periphery of the support in zig-zag shape, an arm secured rotatably in the support. the arm having a contact disposed to engage the wire. and a handle secured to the arm. for its. adjustment.

In testimony whereof I aflix my signature.

JOHN A. NUGENT.

an inspection of 

